• Journal of the Korean Ceramic Society
• /
• v.25 no.5
• /
• pp.443-448
• /
• 1988

Colored Cubic Zircona(CCZ) single crystals were grown by the skull melting method. The grown crystals were doped with up to 0.1wt% transition (Cu, Ni, Co, Ti, Fe, Mo, Cr, V, Mn) metal ions on ZrO2-Y2O3(9.5~10mol%) and their Optical transmission spectra(λ=300~800nm)data were obtained. Various colors were pronounced due to dopant effects in the grown Crystals.

• The Korean Journal of Ceramics
• /
• v.4 no.4
• /
• pp.297-303
• /
• 1998

The effect of aliovalent dopants, $ Nb_2O_5$ and MnO, on the phase stability of 12 mol% ceria partially-stabilized zirconia (Ce-TZP) polycrystals was studied. Both dopants (MnO and $ Nb_2O_5$) significantly increased the stability of the tetragonal zirconia phase (Mb temperature lower than liquid nitrogen temperature). The enhancement of the stability of the tetragonal phase in Ce-TZP doped with 1 mol% of Mno(Ce-TZP/MnO) andCe-TZP doped with 1 mol% of $ Nb_2O_5$(Ce-TZP/$ Nb_2O_5$) were explained by the significant reduction of the driving force, -${\Delta}$Gchem, for the tetragonal-to-mono-clinic phase transformation caused by the addition of MnO and $ Nb_2O_5$. The enhanced stability of the tetragonal phase in the Ce-TZP and Al2O3 composite (Ce-TZP/$Al_2O_3$) is believed to be caused by smaller grain size, moderate reduction in the chemical driving force and increase in the strain energy barrier to the transformation. Mechanical properties of the Ce-TZP and the Ce-TZP/$Al_2O_3$ with (i) the same grain size and (ii) the same Mb temperature were examined by measuring stress-strain behavior in 3 point bending. The Ce-TZP/$Al_2O_3$ composite doped with 1.3w% MnO (Ce-TZP/$Al_2O_3$/MnO), which had the same grain size as the Ce-TZP and De-TZP/$Al_2O_3$ showed more transformation plasticity than either the Ce-TZP or the Ce-TZP/$Al_2O_3$ composite. The Ce-TZP wihch had the same Mb temperature as that of the Ce-TZP/$Al_2O_3$/MnO did not show any transformation plasticity.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.13 no.5
• /
• pp.205-210
• /
• 2003

Alexandrite-like cubic zirconia single crystals were grown by skull melting method. The R.F. generator (output power is 35 ㎾) used for skull melting was operated at 2 MHz. The grown crystals were doped with up to 1 or 1.5 wt% and 0.5 or 1 wt% of rare earth metal ion (Pr, Nd) on$ ZrO_2-Y_2O_3$ (12 mol%). The grown crystals were cut for slice (0.25 mm) and round brilliant (12 mm in diameter). The cut stones were heat treated in air and nitrogen at $1000^{\circ}C$ for 2 hours and their optical absorption spectra ($\lambda$ = 400∼700 nm) data were obtained.

• The Korean Journal of Ceramics
• /
• v.6 no.2
• /
• pp.150-154
• /
• 2000

Mobilities of electrons ($\mu_p$) and holes ($\mu_p$) in 2, 5, and 10 mol% $TiO_2$-doped yttria stabilized zirconia (TD-YSZ) have been estimated by a non-steady state gas permeation method using models proposed by Weppner and Maruyama. Values of $\mu_n$ and $\mu_p$ were found to be closed to those in non-doped YSZ reported earlier. The concentration of electrons and holes were calculated from $\mu_n$ and $\mu_p$ values and the partial conductivities of electrons and holes measured by a dc-polarization method. The concentration of electrons at unit oxygen partial pressure increased with increasing $TiO_2$concentration, while the hole concentration was almost independent of $TiO_2$concentration.

• Journal of the Korean Ceramic Society
• /
• v.29 no.2
• /
• pp.119-126
• /
• 1992

3 mol% Y2O3-doped ZrO2 powders were prepared by hydrolysis with 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 mol/ιH2O/ethanol into 0.1 mol/ι zirconium and yttrium alkoside/ethanol. Spherical monodispersed yttria-partially stabilized zirconia particles with an average diameter of about 0.5 ${\mu}{\textrm}{m}$ were prepared by hydrolysis with 0.2 mol/ιH2O/ethanol. The as-prepared powder was amorphous and with heating it transformed into cubic up to 80$0^{\circ}C$ and into tetragonal over 100$0^{\circ}C$. 3 mol% Y2O3-doped ZrO2 powders calcined over and up to 80$0^{\circ}C$ were a mixture of tetragonal and monoclinic and only tetragonal as determined by X-ray diffraction, respectively.

• Journal of the Korean Ceramic Society
• /
• v.33 no.11
• /
• pp.1223-1230
• /
• 1996

• Proceedings of the Korean Ceranic Society Conference
• /
• 2003.10a
• /
• pp.218.2-218
• /
• 2003

• Proceedings of the Korean Ceranic Society Conference
• /
• 2003.10a
• /
• pp.41.1-41
• /
• 2003

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.20 no.4
• /
• pp.159-163
• /
• 2010

Co-(0.5 mol%) and Ce-(0~0.3 mol%) doped cubic zirconia ($ZrO_2:Y_2O_3$=64:36 mol%) single crystals grown by a skull melting method were heat-treated in $N_2$ at $1200^{\circ}C$ for 3 hrs. The brown-colored as-grown single crystals were changed into either green or blue color after the heat treatment. Before and after the heat treatment, the YSZ (yttriastabilized zirconia) single crystals were cut for wafer form (${\phi}7mm{\times}t2mm$) and round brilliant cut ($\phi$ 12 mm). The optical and structural properties were examined by UV-VIS spectrophotometer and X-ray diffraction. Absorption by $Ce^{3+}(^2F_{5/2},\;_{7/2}(4f){\rightarrow}^2T_g(5d^1)),\;Co^{2+}(^4A_2(^4F){\rightarrow}^4T_1(^4F)$ or $^4T_1(^4P))$ and $Co^{3+}$, change of ionization energy and lattice parameter were confirmed.

• Journal of the Korean Ceramic Society
• /
• v.54 no.5
• /
• pp.413-421
• /
• 2017

In this work, we studied a fluorite structure oxides: Yttria stabilized zirconia, (YSZ); Gd doped $CeO_2$ (GDC); erbia stabilized $Bi_2O_3$ (ESB); Zr doped erbia stabilized $Bi_2O_3$ (ZESB); Ca doped erbia stabilized $Bi_2O_3$ (CESB) in the temperature range of 250 to $600^{\circ}C$ using electrochemical impedance spectroscopy (EIS). As is well known, grain boundary blocking effect was observed in YSZ and GDC. However, there is no grain boundary effect on ESB, ZESB, and CESB. The Nyquist plots of these materials exhibit a single arc at low temperature. This means that there is no space charge effect on ${\delta}-Bi_2O_3$. In addition, impedance data were analyzed by using the brick layer model. We indirectly demonstrate that grain boundary ionic conductivity is similar to or even higher than bulk ionic conductivity on cubic bismuth oxide.